1. Field of the Invention
The present invention relates to an optical information recording/reproducing apparatus for optically recording information on and/or reproducing information from an information recording medium.
2. Related Background Art
FIGS. 1A and 1B are block diagrams showing the arrangement of a conventional magneto-optical disc apparatus. The magneto-optical disc apparatus is disclosed in "Magneto-optical Disc Apparatus", 148-th Oki Denki Gihou, Vol. 57, No. 4. The magneto-optical disc apparatus shown in FIG. 1 is mainly constituted by a control unit A, a drive unit B, and a power source unit 32.
The control unit A comprises an SCSI controller 1, a buffer memory 2, a drive control unit 21 for controlling data transfer to the drive unit B, and the action of the drive unit B, an ECC processing unit 31 for performing error correction of reproduced data, a buffer control unit 30 for controlling the data buffer, a microprocessor 20 for controlling these units, and the like. A medium loading/ejecting mechanism 10 is arranged in the drive unit B. With this mechanism, a magneto-optical disc 16 can be loaded into and ejected from the drive unit main body. The magneto-optical disc 16 is rotated at a predetermined velocity by the drive action of a disc rotation mechanism 9. An external magnetic field (magnetic head) is arranged above the upper surface of the magneto-optical disc 16, and an optical head including an optical system 14 and an actuator 12 is arranged below the lower surface of the magneto-optical disc 16. The optical system 14 includes a semiconductor laser serving as a light source, an objective lens for focusing a laser beam from the semiconductor laser to a very small beam spot, a photosensor for detecting light reflected by the magneto-optical disc 16, and the like. A servo control unit 22 performs tracking control and focusing control of the beam spot of the optical system 14 on the basis of the detection signal from the photosensor.
When information is recorded on the magneto-optical disc 16, recording data is modulated by a signal processing unit 15, and the intensity of the beam spot of the optical system 14 is modulated on the basis of the modulated signal. The beam spot is irradiated onto the magneto-optical disc 16, and a predetermined external magnetic field is applied to the disc 16, thereby recording an information train on an information track. On the other hand, when recorded information is reproduced, the optical system 14 irradiates a laser beam of a reproduction power, and the signal processing unit 15 performs predetermined signal processing on the basis of the detection signal from the photosensor, thereby reproducing recorded information. Reproduced data is transferred to a host computer via the control unit A. The respective units described above of the drive unit B are controlled by a microprocessor 23.
However, the conventional magneto-optical disc apparatus requires microprocessors respectively in the control unit and the drive unit. Although not shown, these microprocessors inevitably require memories for storing programs, variables, and the like, and these memories must be arranged in both the drive unit and the control unit. Furthermore, the drive control unit 21 is required to smoothly control the control unit and the drive unit. As described above, the conventional magneto-optical disc apparatus requires a plurality of microprocessors and memories, and the drive control unit. Therefore, it is difficult to attain cost and size reductions of the apparatus.